Ventilation control apparatus and method

ABSTRACT

An environmental control system for a telecom shelter integrates with a native HVAC system for exchanging interior air in a conditioned space in a machine room, telecom enclosure, or other closed machine environment by forcing or directing cooler outside air to replace interior air without active refrigeration by the native HVAC system. Primary cooling and heating of the conditioned space in the enclosure is performed by an exchange system and control logic that identifies, based on sensory input, when outside air exchange is more efficient than native AC (Air Conditioner) operation. The native AC system is suppressed or inhibited, and primary environmental control performed by fan driven exchange of outside air with air in the enclosure. Sensors and timers identify appropriate periods to defer control to the native AC system for cooling demand in excess of outside air exchange capability, and also identify ongoing suppression, or “takeback” of cooling control from the native system when erroneous, erratic or mistaken operation results in excessive or insufficient cooling, resulting from such factors as equipment failure, operator error, and environmental/disaster occurrences.

RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(e) of U.S.Provisional Patent Application No. 62/081,727 filed Nov. 19, 2014,entitled “EQUIPMENT ROOM VENTILATION CONTROL,” and U.S. ProvisionalPatent Application No. 62/081,730 filed Nov. 19, 2014, entitled “MACHINEROOM HVAC SUPERCESSION CONTROL,” both incorporated herein by referencein entirety.

BACKGROUND

Electronic equipment generates heat as a by-product of electrical flow.As modern technology allows for more densely arranged elements such asmemory and processors on circuit boards, the electrical consumption andcorresponding generated heat increases. In a computer supportedenvironment, electronic equipment such as computers, routers, switchesand other telecommunications equipment is often stored in a “machineroom” that has a separate ventilation, or HVAC (Heating, Ventilation andAir Conditioning) system than the rest of the building, office, orstructure. However, modern proliferation of mobile devices requirescontrolled environment structures for on-site electronic switching andcontrol equipment for telecommunications, such as machine rooms (telecomshelters) for housing switching equipment at cell phone towers, forexample. Such machine rooms typically house a dense configuration ofelectronic equipment, since accommodation of human workers is generallynot required except for occasional maintenance. HVAC demands of thesesmall, specialized machine rooms are particularly specialized andintense due to the small conditioned space and significant heatgeneration capability of the equipment stored therein.

SUMMARY

A supplemental cooling system for a telecommunications equipmentenclosure manages cooling resources for electronic equipment byidentifying a thermostatic control to a native cooling resource directedto the telecommunication equipment enclosure, and interfacing with thethermostatic control for superseding the thermostatic control to enableand disable the cooling resource according to air exchange logic. Airexchange logic performs selective disabling, based on an interiortemperature of the equipment enclosure and an ambient temperatureoutside the equipment enclosure, of the native cooling resource in favorof ambient air exchange with the equipment enclosure. The air exchangelogic then monitors the interior temperature for determining when tore-enable the native cooling resource.

Upon disabling the native cooling resource, the air exchange logic setsan override timer, and evaluates, upon expiration of the override timer,continued suppression of the native cooling resource to determine if atransient or temporary condition has subsided. The air exchange logicdetermines whether the native cooling resource should be re-enabled tomaintain adequate temperatures in the equipment enclosure, and if so,re-enables the native cooling resource. Such transient conditionsinclude excessive compressor head pressure or frozen coils, for example,that if not mitigated as disclosed herein, could persist and exacerbatecooling problems or equipment overheating and failure.

Upon re-enabling the native cooling resource to commence coolingoperations, the air exchange logic sets a takeback timer forreevaluating continued performance of the native cooling resource, andsubsequently disables, if a condition resulting in the previousdisabling of the native cooling resource persists, the native coolingresource, since the previous inhibiting of the native control accordingto the override timer may have not cured the problem or malfunction. Theair exchange logic then continues management of the interior temperatureusing the ambient air exchange for mitigating high temperatures as muchas possible until a more thorough diagnostic is available. Such airexchange, however, nonetheless exhausts heat and may provide adequatecooling, depending on the outside ambient temperature, and is certainlyan improvement over the heat buildup that would otherwise occur in theclosed machine room.

Configurations herein are based, in part, on the observation thatcontrolled environment structures for electronic equipment often employHVAC (heating/ventilation/air conditioning) equipment disproportionateto the air volume of an enclosure defined by the interior of thestructure. These specialized installations are typically unattended andhave HVAC systems sized for a worst-case scenario. Often, such an HVACsystem has a capacity in excess of that required for sufficientlycooling the cubic foot volume of the enclosure. Unfortunately,conventional approaches to machine enclosure cooling suffer from theshortcoming that the native HVAC system cannot be effectively scaledbased on demand, resulting in excessive cooling of the equipmentenclosure. Therefore, such native HVAC systems may be governed bycontrol equipment that is inefficient or wasteful in providingappropriate cooling to the enclosure, and in extreme circumstances mayresult in overcooling and/or overheating of the enclosure, placingsensitive electronic equipment at risk of damage from excessiveoperating temperatures.

Accordingly, configurations herein substantially overcome theabove-described shortcomings by providing a system, method and apparatusfor invoking an external air exchange with a conditioned space in theenclosure when doing so provides more efficient environmental andtemperature controls for keeping the interior at an acceptabletemperature. An override and takeback setting actively manage andcontrol the native HVAC system to correct short term problems oranomalies and prevent ongoing inefficient operation using a takebackinterval that assesses remedial measures for effectiveness.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following description of particularembodiments of the invention, as illustrated in the accompanyingdrawings in which like reference characters refer to the same partsthroughout the different views. The drawings are not necessarily toscale, emphasis instead being placed upon illustrating the principles ofthe invention.

FIG. 1 is a context diagram of a telecommunications environment suitablefor use with configurations disclosed herein;

FIG. 2 is a plan view of an equipment enclosure in the environment ofFIG. 1;

FIG. 3 is a block diagram of a configuration in an equipment enclosureas in FIG. 2; and

FIGS. 4A and 4B are a flowchart of operation of a management circuit andapplication in the equipment enclosure of FIG. 3.

DETAILED DESCRIPTION

Electronics equipment for telecommunications is often located at atransmission point defined by an antenna, cell tower, or an intermediaterouting location. Small, specialized enclosures or machine rooms providea protective, temperature controlled environment that is vital tocontinued operation of the equipment. Since such enclosures may beremote, and only periodically monitored by an on-site technician, anative control system for providing HVAC support is intended to provideautonomous operation. Further, due to the size and number of equipmentenclosures, rigorous attention to HVAC systems serving individualenclosures presents a logistical challenge. Additionally, such sheltersare built according to standard configurations that must account forworst case conditions including heat load, geography, condition of theHVAC (age degradation) and solar gain based on time of day and year andlocal shade casting elements such as buildings, trees, etc., thattypically do not apply equally to all shelters. Accordingly, inefficientor underperforming installations may elude detection until outrightfailure, placing the equipment therein at risk. Configurations belowprovide a supplemental management and oversight approach that increasesefficiency and longevity of the native control HVAC system, alerts as tofunctional deficiencies, and mitigates cooling shortfalls in the eventof failure.

Environmental control of telecommunications (telecoms) enclosuresbenefits from the observation that substantial equipment cooling mayoften be achieved by ventilating with ambient air for replacing heatedmachine room air through a system of fans and louvers. One such approachis outlined in U.S. Pat. No. 8,770,493, filed Oct. 10, 2012, entitled“TELECOM SHELTER COOLING AND CONTROL SYSTEM.” While not alwaysapplicable as an exclusive cooling approach, strategic use of ambientair exchange reduces the usage time and power cycles imposed on thenative control. In the approaches discussed further below, supplementalair exchange is performed in conjunction with sensor based diagnosticand monitoring of the enclosure for overriding the native control infavor of ambient air exchange, and selectively inhibiting and enablingoperation of the native control. In conjunction with air exchange logicfor interpreting sensor data such as temperature and humidity, thenative control is monitored in a supervisory capacity within certainpredetermined limits of temperature and/or humidity. Intervention inresponse to detected inefficiency or operational problems disables thenative control for mitigating a temporary malfunction or anomaly. Theair exchange logic re-enables the native control, subject to a takebackof control if the detected inefficiency or malfunction persists.

In a typical operating scenario according to configurations herein, acontroller having air exchange logic disables, based on an interiortemperature of the equipment enclosure and an ambient temperatureoutside the equipment enclosure, the native cooling resource in favor ofambient air exchange with the equipment enclosure, and monitors theinterior temperature for determining when to re-enable the nativecooling resource. Upon disabling the native cooling resource, the airexchange logic sets the override timer and re-enables the native coolingresource. Suspending operation of the native control includesinterfacing with a thermostatic circuit for overriding a thermostaticswitch to disable the native control as described further below.

Following expiration of the override timer, the air exchange logic mayconclude that the native control is capable of again maintaining thetemperature within the predetermined limits, and re-enables the nativecontrol subject to a takeback timer. Upon expiration of the takebacktimer, the air exchange logic again disables, if a condition resultingin the previous disabling of the native cooling resource persists, thenative cooling resource.

The examples below depict several configurations, typically for coolingas equipment heat generation is a paramount concern, and provide amethod and apparatus for implementing the proposed approach. Alternatearrangements of HVAC control, such as additional environmental sensorsand circuits for interfacing with the native control, could beimplemented according to the principles herein.

FIG. 1 is a context diagram of a telecommunications environment suitablefor use with configurations disclosed herein. Referring to FIG. 1, in atelecommunications environment 100, an enclosure 110 houses a machineroom 112 for storing and operating communications equipment 120, such asswitching and routing equipment, power supplies, antenna amplifiers, andassociated computers and processing devices. A HVAC system 130 providesthe native control and includes an evaporator 132 and fan 133 forblowing cooled air, a compressor 136, a condenser 134 outside theenclosure, and a thermostat 138 or other control for switching thecompressor 136 and other HVAC components. The cooling operation of theHVAC system 130 is generally the most used, to offset the high heatgiven off by the equipment 120.

A controller 150 in the enclosure 110 includes air exchange logic 152(FIG. 2) in the form of a circuit and/or application, and operates theintake fan 154 and controls the HVAC system 130 via an interface 160 tothe thermostat 138 for providing thermostatic control over the HVACsystem 130. An intake vent 156 and output vent 158 isolate the machineroom 112 when the intake fan 154 is idle, such as by louvers, gates,panels or other automated closures.

A telecommunications tower 170, such as a cell tower or TV/radiotransmission beacon is responsive to the equipment 120 for throughputsupport, and AC lines 172 provide electrical power. A local antenna 174provides Internet connectivity for the controller via WiFi or 4GLwireless links under IEEE 802.11 connectivity; alternatively a hardwiredEthernet cable or other Internet LAN may also be provided alternatively,form C contacts may be employed for communicating alarms and status.

FIG. 2 is a plan view of an equipment enclosure in the environment ofFIG. 1. Referring to FIGS. 1 and 2, an example machine room includes anative control HVAC system 130 having a single compressor 136 andthermostat 138. The controller 150 connects to the thermostat 138 viathe interface 160, and also connects to temperature sensors (such asthermistors) 151-1 and 151-2, for sensing interior temperature in theenclosure 110, and 151-3 (151 generally) for sensing ambient temperatureoutside the enclosure 110. Note that outside air thermistor 151-3 may bedisposed at the intake vent 156 to avoid running exterior wires throughthe enclosure 110 wall, and is coordinated with opening of the vent,discussed below.

Intake vent 156 and output vent 158 are also responsive to thecontroller 150, and coordinate with the intake fan 154 for exchangingambient air. Alternatively, the intake fan 154 could be mounted as anexhaust fan, as long as an airflow path for ambient air is provided. Airexchange logic 152 in the controller 150 receives input from thethermistors 151 and the thermostat 138 for computing a current state andneed for ambient exchange and control of the compressor 136 (nativecontrol), as discussed further below. Actuators 180 responsive to thecontroller 150 open and close the vents 156, 158.

FIG. 3 is a block diagram of a configuration in an equipment enclosureas in FIG. 2. Referring to FIGS. 2 and 3, enclosures 110 vary in sizeand may take the form of a small cabinet up to human accessible roomshaving rows of equipment. A typical communications equipment enclosureor shelter is disposed at the base of the tower or antennas it supports,and is large enough to accommodate one or 2 technicians for limitedaccess to the equipment therein. Depending on the size, and thereforethe cooling demand, multiple compressors 136-N may be used forredundancy and/or increased thermal response. The multiple compressors156-N may have an integrated native control, or may operate separatelyat different ranges of temperature to implement a “phase in” as demandincreases. It is, however, often desirable to commonly manage multiplecooling resources for load sharing to prevent unbalanced usage, and thuswear, on the compressor, such as a compressor with a lower turn-ontemperature set point that is always to be invoked first.

For example, the native control 130 may include a plurality ofindependently switchable compressors 136, and suspending operationincludes identifying a power cycle count and an elapsed time count foreach of the plurality of compressors, and alternating enablement of eachcompressor of the plurality of compressors 136 for achieving an evendistribution of operational time and/or cycling. This ensures thatswitching and override of the native control 130 as described hereinwill not resort to always restarting the same compressor, 136, resultingin an uneven load, but will instead distribute the burden evenly.

Continuing to refer to FIG. 3, the controller 150 is responsive to amanagement station 153, such as a separate controller, laptop, PC orserver having control software/firmware, data storage, and programs forreceiving, analyzing, and responding to sensor data (thermistors,humidity sensors, switches, etc.) and control objects such as thecompressors, fans, louvers and gates in the enclosure 112. A GUI 155(Graphical User Interface) provides an interactive operator withsettings and controls for examining and updating system parameters suchas temperature thresholds (set points) and timeouts that affectoperation of the air exchange logic 152.

The controller 150 may be a server, integrated circuit, firmware orother suitable processing device for implementing the air exchangelogic. The controller 150 includes an override timer 182 and a takebacktimer 184 for implementing the respective intervals for inhibiting andenabling the compressors 136. The timers 182, 184 may be implemented ashardware or software registers, firmware values or other suitableimplementation.

Each compressor 136-1 . . . 136-N (136 generally) has one or morethermostats 138-1 . . . 138-N for sensing temperatures in the machineroom 112, and interfaces with the controller 150 via the interface 160and feedback indicator 161. In the example configuration, the interface160 opens and closes a thermostat circuit to which the compressor 136responds, although other mechanisms for enabling and inhibiting(suppressing) compressor operation may be invoked. The feedbackindicator 161 indicates when each compressor 138-N is commanded to an“on” state by the native control, and is used to track power cycles anduptime.

In certain configurations, the machine room 112 employs a plurality oftemperature sensors (such as thermistors) 151 for each installation orcontroller 150. Placement and readings from the sensors 152 includeinvoking the ambient air circulation fan 154 for obtaining a truereading from an ambient air temperature sensor disposed adjacent to theambient air circulation fan 154, to provide a true reading withoutrequiring exterior mounting. The air exchange logic 152 then employs alowest reading from among each sensor 151 of a plurality of interiortemperature sensors for initiating the ambient air circulation forcooling the enclosure, based on a sensed ambient temperature and asensed enclosure temperature obtained from the plurality of sensors, andemploys a highest reading from among each sensor of a plurality ofinterior sensors for halting the ambient air circulation, for ensuringan inaccurate sensor reading is ignored. Strategic placement of sensors151 to cover range variations in temperature assures that an accuratereading of environmental conditions in the enclosure 110 is computed bythe air exchange logic 152.

Sensor information such as temperature, humidity and airflow thereforederives from the temperature or other sensors placed in the conditionedspace and outside of the enclosure to determine a delta or difference tohelp identify expected changes in the conditioned space will result fromexchange with the outside air. Placement of exterior sensors issensitive to solar load and shifting with shadows due to solar movement,wind, and snow/icing conditions, which can vary based on exteriorexposure to sun and wind.

In an example arrangement, sensor or thermistor 151 readings fordetermining adequate temperatures are defined by a range between amaximum set point and a minimum set point, and monitoring includes ameasurement of an interior temperature inside the machine room, ameasurement of exterior temperature of ambient air outside the machineroom 112, and a correction interval such as the override timer forpermitting the native control to remain idle.

In the example configuration identifying the power cycle and elapsedtime includes interfacing with the thermostatic circuit for determiningenablement of the compressors, and receiving a rectified signal over asingle conductor from a plurality of thermostatic switches foridentifying which thermostatic circuits are enabling the respectivecompressors. A single conductor and signal may be employed by connectinga rectifier 165-1 . . . 165-N to an energized conductor from thethermostat 138, and varying the rectification (half wave, quarter wave,etc.) for each compressor 136. In a typical installation, the nativeHVAC system (native control) 130 operates on a 24VAC thermostaticcircuit. Identifying the power cycle and elapsed time includesinterfacing with a thermostatic circuit for determining enablement ofthe compressors, as the thermostat 138 return line will only register24VAC when energized. Rectifiers 165 connected between the thermostat138 return line and the controller 150 receive a rectified signal over asingle conductor from a plurality of thermostatic switches 138 foridentifying which thermostatic circuits are enabling the respectivecompressors 136. The rectified connection has a varying response basedon the thermostatic circuit The rectified signals will aggregate suchthat multiple compressor “on” signals generate different wave formsdepending on which compressors are powered on, and the controller 150reads the individual, aggregate signal on the feedback indicator 161 toascertain compressor operation.

The intake vent 156 and exhaust (output) vent 158 may be louvers, gates,or closures responsive to the controller 150. Each of the vents 156, 158should remain closed when ambient air exchange is not occurring, toavoid loss of cooled air and for conformance with fire suppressionregulations. Multiple vents may be employed. In a particularconfiguration, the vents 156, 158 have a counterbalanced panel closuresuch as that disclosed in co-pending U.S. patent application Ser. No.14/______,______ , incorporated herein by reference.

Temperature sensors 151-1 . . . 151-N may be for sensing interior orexterior temperature, and may vary in number to account for so-called“hot spots” which offer skewed or erratic readings. For example, anexterior thermistor in direct sunlight will tend to read a higher thanactual temperature. Similarly, an interior thermistor closer to the pathof cooled air may give an artificially reduced reading then the machineroom 112 as a whole.

Accordingly, the air exchange logic 152 employs a plurality ofthermistors 151 (or other temperature sensing device) for eachcompressor 136 in the native control 130. The air exchange logic 151 mayinvoke the ambient air circulation fan 133 for obtaining a true readingfrom an ambient air thermistor disposed adjacent to the ambient aircirculation fan 133, as thermistor 151 placement adjacent to (or within)the intake vent 156 avoids wiring outside of the enclosure 110 forexternal thermistors.

Such placement may be, for example, inside the fan tray of the intakefan, which is beneficial for at least 2 reasons: 1) Accuracy ofmeasurement. The outside air temp thermistor can influenced by solarloading and radiated heat (off the building, door &/or adjacentequipment) so it can be moved inside the fan tray to minimize theseinfluences; and 2) Ease of installation. The outside air temperaturesensor can now be factory installed and it is no longer necessary todrill holes in the shelter to place it, or to be concerned withinconsistent placement by different installers.

When multiple temperature sensors are used, the air exchange logic mayemploy a lowest reading from among each sensor of a plurality ofinterior sensors for initiating the ambient air circulation for coolingthe enclosure. Similarly, it may employ the highest reading from amongeach sensor of a plurality of interior sensors for halting the ambientair circulation, for ensuring an inaccurate sensor reading is ignored.Similar placement considerations and reading applies to the exteriortemperature readings.

FIG. 4 is a flowchart of operation of a management circuit andapplication in the equipment enclosure of FIG. 3. Referring to FIGS. 3and 4, the disclosed method of managing cooling resources or acompressor 136 for cooling electronic equipment 120 includes identifyinga thermostatic control 138 to a native cooling resource, such as acompressor 136, directed to a telecommunication equipment enclosure 110,and interfacing with the thermostatic control 138 for superseding thethermostatic control 138 to enable and disable the cooling resourceaccording to air exchange logic 152, as disclosed at step 200. Thethermostatic control 138 may be a conventional 24v on/off circuit, ormay be part of a more elaborate demand computation. The air exchangelogic 152 monitors the temperature in the machine room 112 for deviationfrom the predetermined limits, as depicted at step 201. Thepredetermined limits include temperature, as measured by sensors (suchas thermistors) 151, and may also include other factors such ashumidistats for humidity or any suitable environmental aspect.

In a particular example, predetermined limits encompass temperature, andinclude identifying a high set point defining a temperature at which thenative control is invoked for cooling the machine room, and identifyinga low set point defining a temperature at which the native control isdisabled. The high set point and low set point therefore identify arange of operation included in the predetermined limits for ambient aircirculation in favor of native control.

The air exchange logic 152 determines when the native control of theHVAC system 130 is operating outside of predetermined limits fortemperature, as shown at step 202 and the air exchange logic 152suspends operation of the native control in favor of ambient aircirculation by exchanging outside air, as depicted at step 203. If thenative control is operating within the predetermined limits, controlreverts to step 201 for continued monitoring.

In particular configurations, concluding the capability of the nativecontrol further includes comparing the temperature of ambient airoutside the machine room 112 with a maximum interior temperature, anddetermining that ambient air circulation provides insufficient coolingcapacity, resulting in a switch over from ambient air circulation backover to the native control 130.

However, an improperly sized native control 130 may result in anovercooling situation. In such an instance, determining when the nativecontrol is outside the predetermined limits includes comparing thetemperature of the machine room 112 resulting from the native control130 to a minimum interior temperature, and determining a cooling effectfrom the native control is in excess of a need for maintaining theminimum interior temperature because of bringing the machine room 112temperature down too quickly.

The air exchange logic 152 sets an override timer 182 corresponding to acondition resulting in a deviant parameter associated with the operationoutside of the predetermined limits of native control operation, asshown at step 204. In response, the air exchange logic inhibitsoperation of the native control for the duration of the override timer182, as depicted at step 205. The override timer 182 is set to allowtemporary conditions such as excessive backpressure in the compressor136 or coil freezing to abate, and in a typical scenario may be in therange of 3-30 minutes, although any suitable value may be used. Somefault conditions exacerbate from attempted continued operation, andrequire only an idle period of the native control for self-correction.Otherwise, in the absence of the inhibit mode disclosed herein, thefault condition would persist and compromise the equipment 120 or theability to control the environment of the enclosure 110.

Using the example above, the air exchange logic 152 may identify a shortcycling and overcooling condition in the enclosure based on a pluralityof occurrences of operation outside of the predetermined limits fortemperature. The air exchange logic 152 sets the override timer 182based on a duration for allowing ambient air circulation to maintain thetemperature in the enclosure 110 below a maximum set point without powercycling a compressor in the native control. The predetermined limitssuch as temperature also pertain to environmental conditions in theenclosure and the deviant parameter includes at least one of excessivelycold or hot interior temperature, excessive humidity, airflow orexcessive cycling of a refrigerant compressor of the native control.

For example, the air exchange logic performs a hysteresis analysis ofpower cycles and elapsed time during each power cycle of thecompressors, and may conclude that a short cycling pattern is causingoperation outside of the predetermined limits by a disproportionatecooling effect from the elapsed time. The native AC unit may beoversized and is rapidly bringing down the temperature in a short timewithout proper dehumidification. In such an instance, the air exchangelogic inhibits operation of the native control for extending a cycletime without significant deviation from the predetermined limits oftemperature. This allows ambient air exchange until a temperaturesetpoint just short of an excessive level, thus resulting in longercycle times.

The air exchange logic 152 evaluates, upon expiration of the overridetimer 182, continued suppression of the native cooling resource 130, asdepicted at step 206. This includes determining, with the air exchangelogic 152, whether the native cooling resource 130 should be re-enabledto maintain adequate temperatures in the equipment enclosure 110, asshown at step 207. A check is performed, at step 208, and the airexchange logic 152 re-enables the native control 130 upon expiration ofthe override timer 182 based on observed correction of the deviantparameter that resulted in operation outside the predetermined temperaterange or other environmental conditions, as disclosed at step 209. Ifthe condition has not abated, ambient air management is used to mitigateexcessive temperatures, as discussed below with respect to step 214.

Upon re-enabling the native cooling resource 130, the air exchange logic152 sets a takeback timer 184 for reevaluating continued performance ofthe native cooling resource 130, as disclosed at step 210. This includessetting the takeback timer 184 corresponding to a condition resulting inobserved diminished performance, as depicted at step 211. Conditionsresulting in diminished performance and/or deviant parameters includeexcessive cooling causing increased humidity, such as a short intervalof cooling that drops the temperature but fails to condense moisturefrom the air. The air exchange logic 152 permits operation of the nativecontrol for the duration of the takeback timer 184 to ascertain if thecondition causing the diminished performance has abated, as depicted atstep 213.

A check is performed, at step 213, to identify if the condition hasabated and if the system is again operating within normal parameters. Ifso, control reverts to step 201 for continued monitoring in a supervisorstate, in which the air exchange logic 152 monitors but does notintervene in native control 130 operation.

If the check at step 213 did not indicate correction, then the airexchange logic 152 re-inhibits the native control 130 at the expirationof the takeback timer 184 if the condition persists as depicted at step214, and continues management of the interior temperature using theambient air exchange for preventing hardware overhearing, as disclosedat step 215. Ambient air exchange can effectively provide sufficientcooling depending on the differential between ambient (outside) air andthe machine room 112 temperature resulting from equipment generatedheat. Various alarms and notifications are also generated to alertmonitoring personnel or equipment, and continued increased heat mayresult in equipment 120 shutdown to prevent damage.

Several example use cases of operational scenarios are as follows. Whenthe fans are running, the outside air stream temperature can be sampledcontinuously. When the fans aren't running [such as when the HVACs arerunning or when the air temperature inside is below either a. an airconditioner maximum cooling threshold (the low end of the control rangewhere the HVACs are re-inhibited) or b. the air conditioner Ontemperature threshold] the outside air is sampled periodically byrunning the fans for a brief period (long enough to allow thetemperature sensor to respond and settle at a temperature reading thatmore accurately reflects the outside air temperature). Samples are alsotaken when mode changes occur (such as switching to/from Aircon mode orAircon Too Cool mode or Direct Air mode). A “freshness” metric avoidsunnecessary sampling if the last sample was taken recently enough to bevalid for control purposes. Logic to suspend sampling when the insideair temp drops below the fan On temp threshold is also implemented. Inthis way, he inside temperature will not be driven even lower bysampling outside air periodically when outside air temperatures are low(recall that the fans turn on at low speed when sampling and that coulddrop inside the inside temperature if it is really cold outside and theheat load inside is too low to warm the inflow of the cold airsufficiently).

Alternate configurations of the invention include a multiprogramming ormultiprocessing computerized device such as a multiprocessor, controlleror dedicated computing device or the like configured with softwareand/or circuitry (e.g., a processor as summarized above) to process anyor all of the method operations disclosed herein as embodiments of theinvention. Still other embodiments of the invention include softwareprograms such as a Java Virtual Machine and/or an operating system thatcan operate alone or in conjunction with each other with amultiprocessing computerized device to perform the method embodimentsteps and operations summarized above and disclosed in detail below. Onesuch embodiment comprises a computer program product that has anon-transitory computer-readable storage medium including computerprogram logic encoded as instructions thereon that, when performed in amultiprocessing computerized device having a coupling of a memory and aprocessor, programs the processor to perform the operations disclosedherein as embodiments of the invention to carry out data accessrequests. Such arrangements of the invention are typically provided assoftware, code and/or other data (e.g., data structures) arranged orencoded on a computer readable medium such as an optical medium (e.g.,CD-ROM), floppy or hard disk, flash drive or other medium such asfirmware or microcode in one or more ROM, RAM or PROM chips, fieldprogrammable gate arrays (FPGAs) or as an Application SpecificIntegrated Circuit (ASIC). The software or firmware or other suchconfigurations can be installed onto the computerized device (e.g.,during operating system execution or during environment installation) tocause the computerized device to perform the techniques explained hereinas embodiments of the invention.

While the system and methods defined herein have been particularly shownand described with references to embodiments thereof, it will beunderstood by those skilled in the art that various changes in form anddetails may be made therein without departing from the scope of theinvention encompassed by the appended claims.

What is claimed is:
 1. A method of managing cooling resources forelectronic equipment comprising: identifying a thermostatic control to anative cooling resource directed to a telecommunication equipmentenclosure; interfacing with the thermostatic control for superseding thethermostatic control to enable and disable the cooling resourceaccording to air exchange logic; disabling, based on an interiortemperature of the equipment enclosure and an ambient temperatureoutside the equipment enclosure, the native cooling resource in favor ofambient air exchange with the equipment enclosure; and monitoring theinterior temperature for determining when to re-enable the nativecooling resource.
 2. The method of claim 1 further comprising, upondisabling the native cooling resource, setting an override timer;evaluating, upon expiration of the override timer, continued suppressionof the native cooling resource; determining, with the air exchangelogic, whether the native cooling resource should be re-enabled tomaintain adequate temperatures in the equipment enclosure; and enablingthe native cooling resource.
 3. The method of claim 2 furthercomprising, upon re-enabling the native cooling resource, setting atakeback timer for reevaluating continued performance of the nativecooling resource; disabling, if a condition resulting in the previousdisabling of the native cooling resource persists, the native coolingresource; and continuing management of the interior temperature usingthe ambient air exchange.
 4. The method of claim 1 further comprisingdetermining adequate temperatures defined by a range between a maximumset point and a minimum set point, and monitoring includes a measurementof an interior temperature inside the machine room, a measurement ofexterior temperature of ambient air outside the machine room, and acorrection interval for permitting the native control to remain idle. 5.In a machine room enclosure containing electronic equipment conditionedby a native environmental control system for maintaining temperature, amethod for operating the native control system, comprising: determiningwhen the native control is operating outside of predetermined limits fortemperature; suspending operation of the native control in favor ofambient air circulation by exchanging outside air; concluding that thenative control is capable of again maintaining the temperature withinthe predetermined limits; re-enabling the native control; and monitoringthe temperature in the machine room for deviation from the predeterminedlimits.
 6. The method of claim 5 further comprising: setting an overridetimer corresponding to a condition resulting in a deviant parameterassociated with the operation outside of the predetermined limits ofnative control operation; inhibiting operation of the native control forthe duration of the override timer; and enabling the native control uponexpiration of the override timer based on observed correction of thedeviant parameter.
 7. The method of claim 5 wherein concludingcapability of the native control further comprises: comparing thetemperature of ambient air outside the machine room with a maximuminterior temperature; and determining that ambient air circulationprovides insufficient cooling capacity.
 8. The method of claim 5 whereindetermining operation outside of predetermined limits comprises: settinga takeback timer corresponding to a condition resulting in observeddiminished performance; permitting operation of the native control forthe duration of the takeback timer to ascertain if the condition causingthe diminished performance has abated; and re-inhibiting the nativecontrol at the expiration of the takeback timer if the conditionpersists.
 9. The method of claim 8 wherein determining when the nativecontrol is outside the predetermined limits further comprises: comparingthe temperature of the machine room resulting from the native control toa minimum interior temperature; and determining a cooling effect fromthe native control is in excess of a need for maintaining the minimuminterior temperature.
 10. The method of claim 5 wherein suspendingoperation of the native control includes interfacing with a thermostaticcircuit for overriding a thermostatic switch to disable the nativecontrol.
 11. The method of claim 6 further comprising: identifying ashort cycling and overcooling condition in the enclosure based on aplurality of occurrences of operation outside of the predeterminedlimits for temperature, and setting the override timer based on aduration for allowing ambient air circulation to maintain thetemperature in the enclosure below a maximum set point without powercycling a compressor in the native control.
 12. The method of claim 6wherein the predetermined limits pertain to environmental conditions inthe enclosure and the deviant parameter includes at least one ofexcessively cold interior temperature, excessive humidity, airflow orexcessive cycling of a refrigerant compressor of the native control. 13.The method of claim 6 further comprising identifying a high set pointdefining a temperature at which the native control is invoked forcooling the machine room; identifying a low set point defining atemperature at which the native control is disabled, the high set pointand low set point identifying a range of operation included in thepredetermined limits for ambient air circulation in favor of nativecontrol.
 14. The method of claim 5 wherein the native control includes aplurality of independently switchable compressors, and suspendingoperation includes: identifying a power cycle count and an elapsed timecount for each of the plurality of compressors; and alternatingenablement of each compressor of the plurality of compressors forachieving an even distribution of operational time.
 15. The method ofclaim 14 further comprising receiving, from each of the plurality ofcompressors, an aggregated rectified signal over a single conductor,each compressor connected to a separate rectifier for providing adifferent waveform than the others of the plurality of compressors. 16.The method of claim 5 further comprising: performing hysteresis analysisof power cycles and elapsed time during each power cycle; concluding ashort cycling pattern is causing operation outside of the predeterminedlimits by a disproportionate cooling effect from the elapsed time; andinhibiting operation of the native control for extending a cycle timewithout deviation from the predetermined limits of temperature.
 17. Anair exchange controller device for a telecom shelter, comprising: Aninterface to a thermostatic control of a native cooling resourcedirected to a telecommunication equipment enclosure, the interfaceadapted to supersede the thermostatic control to enable and disable thecooling resource according to air exchange logic in a controller; theair exchange logic operable to disable, based on an interior temperatureof the equipment enclosure and an ambient temperature outside theequipment enclosure, the native cooling resource in favor of ambient airexchange with the equipment enclosure; and an override timer for settinga duration of disabling of the native cooling resource, the air exchangelogic further operable to monitor the interior temperature fordetermining when to re-enable the native cooling resource.
 18. Thedevice of claim 17 wherein the air exchange logic is further operable toset the override timer and evaluate, upon expiration of the overridetimer, continued suppression of the native cooling resource; the airexchange logic configured to determine, with the air exchange logic,whether the native cooling resource should be re-enabled to maintainadequate temperatures in the equipment enclosure and to enable thenative cooling resource by directing the interface to the thermostaticcontrol.
 19. The device of claim 18 further comprising a takeback timerin the controller, the takeback timer responsive to the air exchangelogic for, upon re-enabling the native cooling resource, setting thetakeback timer until reevaluation of continued performance of the nativecooling resource; the air exchange logic configured to disable, if acondition resulting in the previous disabling of the native coolingresource persists, the native cooling resource, and to continuemanagement of the interior temperature using the ambient air exchange.20. The device of claim 18 further comprising a sensor indicative of adeviant parameter, the air exchange logic further operable to: set anoverride timer corresponding to a condition resulting in the deviantparameter associated with the operation outside of the predeterminedlimits of native control operation; inhibit operation of the nativecontrol for the duration of the override timer; and enabling the nativecontrol upon expiration of the override timer based on observedcorrection of the deviant parameter.
 21. The device of claim 17 whereinthe interface for suspending operation of the native control includes aninterface with a thermostatic circuit for overriding a thermostaticswitch to disable the native control and a rectified connection to thethermostatic circuit for determining when the thermostatic circuit isenergized, the rectified connection varying a response based on thethermostatic circuit.
 22. A computer program product on a non-transitorycomputer readable storage medium having instructions that, when executedby a processor, perform a method for temperature monitoring and control,the method comprising: determining when a native control is operatingoutside of predetermined limits for temperature; suspending operation ofthe native control in favor of ambient air circulation by exchangingoutside air; concluding that the native control is capable of againmaintaining the temperature within the predetermined limits; re-enablingthe native control; and monitoring the temperature in the machine roomfor deviation from the predetermined limits.